Arthropod Fruit Injury

 

Plum Curculio: I see two forms of PC injury.

1) Typical PC injury is created when the fruit is very young. It is a healed scar, up to one inch (size depends on fruit enlargement) long. It often takes on a D shape, with the flap (under which the egg was laid) still discernable along the straight edge. Sometimes the middle of that straight edge is interrupted by a buldge of grainy tissue (where the egg was). If the egg hatched, the fruit may be gnarled and mis-shapen, and cutting it open may reveal the (now healed) signs of the tunnel made by the larva. 2) Late PC injury is from newly emerged adults (August); a relatively fresh hole 2-3mm in size, usually oval, with some necrotic edges. Skin has not had time to heal over. Location is usually on shoulder of stem end, or on bottom ridge, toward calyx end.

 

Tarnished Plant Bug: TPB injury is a dimple with a grainy spot in the center, OR a grainy spot (roughly round) with a dimple in the center. Often much of the TPB injury in an orchard is hidden in the calyx end, where only inquisitive entomologists would look.

 

European Apple Sawfly: Two Forms: 1) Elongated, curving grainy scar on the fruit surface, which originates in a dimple in the calyx end. 2) Some EAS scars (always in calyx end) are very similar to TPB scars. These are from eggs that didn't hatch, and seem broader, wider than TPB scars.

 

Redbanded Leafroller: Recent surface chewing that removes the skin and a small amount of flesh, and is hidden from light by overlying leaf, or (especially in Cortland) another fruit set immediately behind. (Leafrollers must have shelter from light). The caterpillar is often still present in early September, chewing away.

 

Comstock Mealybug: Sepals in calyx end of fruit are black (covered by sooty mold). Cutting away sepals reveals the whitish mealybug, hidden in the small cavity beneath the sepals.

 

White Apple Leafhopper: Shiny brown flecks of excrement on the upper side of the fruit, below leaves on which the leafhoppers were feeding. As an extra clue, leaves immediately above the affected fruit show white stippling. Heavy rain washes the fruit clean.

Mites: Eggs of European red mite acre obvious as a group in the calyx end of the fruit. They are round, brick red in color. Sometimes mites are abundant enough for these to be obvious on the fruit. The overwintering form of twospotted spider mites are less common, and are orange.

Green Fruitworm: A large, deep, irregular, grainy patch is likely from green fruitworm. The caterpillar consumed part of the fruit early in the year. The injury healed over, leaving a scar that is sometimes very deep, sometimes shallow.

Climbing Cutworm: A recently chewed hole (up to 1/4 inch across) at the bottom ridge could be from climbing cutworms, or occasionally other insects.

Apple Maggot: Most AM injury is hidden from our view, not visable without slicing open the fruit. Sometimes it is visible as a very slight indentation, accompanied by a tiny hole (often need a 2X hand lens to confirm), often accompanied by very slight darkening of the skin around the puncture. Sometimes there is a tiny bit of whitish surface exudate, where juice dried up.

Codling Moth: Codling moth injury on fruit is rare in conventionally managed orchards. Reddish-brown frass (fecal pellets), usually at the calyx end, projects out of the tunnel. Codling moth larvae usually go to the core and do some feeding on the seeds. Occasionally a tunnel is in the stem end of the fruit.

 

Lesser Appleworm: LAW injury is very similar to codling moth damage, with the same red-brown fecal pellets. LAW tunnels are usually shallow, and don't go to the core. They often arise on the side of the apple, rather than being hidden in the stem end or calyx end. If you find the caterpillar, you can distinguish this species from CM by looking at the anal comb (you need a lens or microscope). Most growers don’t care which species it is!

San Jose Scale: The scales themselves are tiny, round, raised and grayish. At the time of harvest, those found on the fruit are roughly 1mm across. They would be hard to spot, except a reddish ring forms around each scale. They are most common toward the calyx end. Where you find one, you’ll usually see others

Rosy Apple Aphid: Cortland is the variety most frequently showing this injury. Fruit adjacent to rosy apple aphid colonies are stunted, puckered at the calyx end, and ridged like a pumpkin.